Precise alignment of two parts of similar shape is needed in a number of situations.
For instance, two capillaries are aligned to secure the smooth through--flow of liquid; two optical fibers are aligned to secure transmission of light in communication cables; two tubes are aligned for precise coaxial welding; two electrical connectors are aligned to secure conduction between corresponding contacts, and so on. Such alignment is more difficult if the parts are very small and/or if the requirement on the precision of the alignment is very high.
The most precise alignment techniques were developed for splicing and connecting optical fibers. Thus, fiber-optics techniques are used herein for illustration of this problem and its state-of-the-art solutions, although it should be understood that this problem, as well as other applications of the present invention, is significantly broader in scope.
Splicing of optical fiber (that is, connecting the fiber ends permanently in a butt-to-butt fashion) is done in a number of ways. Splicing methods can be divided into several groups:
FUSING OR WELDING. Denuded ends of two fibers are aligned precisely under a stereo-microscope by X-Y-Z manipulators, and then welded together by a flame, arc or plasma. Such a manual alignment method is versatile but requires expensive equipment, time and considerable skill of the operator.
EMBEDDING IN CURABLE ADHESIVES. Fibers are aligned by mechanical contact with a precisely shaped solid surface, and then connected by a curable adhesive (such as a two-component epoxy glue). The aligning surfaces have various shapes: V-groove, star-shaped groove, arched groove, precise cylindrical hole, etc. Alignment is dependent upon the precise shape and surface quality of the rigid aligning surface.
DEFORMABLE ALIGNING/CLAMPING. Fibers are squeezed between deformable elements or clamps of various shapes and configurations. The deformation is caused by an external force. The elements may be from an elastomer, a deformable metal. etc. Such elements have a double function (aligning fibers and holding them together and both depend on the precision and surface quality of the element.
MEMORY MATERIAL SPLICERS containing the fiber ends in enlarged cavities which collapse upon heating so that their inner diameter is diminished below the fiber outside diameter. Various "heat shrinkable" materials can be employed, such as memory metals described in U.S. Pat. Nos. 4,261,644; 4,352,542 and 4,597,632 or British Patent No. 1,555,475; crystalline crosslinked polymers described for example in U.S. Pat. Nos. 3,086,242; 3,359,193; 3,370,112; 3,597,372; 3,616,363; 4,178,067; 4,489,217 and 4,725,117; or amorphous inherent memory polymers described for example in U.S. Pat. No. 4,731,079.
One can observe that the apparatus needed for aligning the fibers for fusing or welding is expensive and often requires laboratory conditions as well as the high skill of the operator.
Aligning mechanisms of the mechanical splices (whether using curable adhesives, deformable elements, or memory materials) require parts made with very high precision and thus, are inherently expensive. The alignment depends on the contact of the closest portion: of the aligned parts ("ends") with some portion of the solid aligning surface. The alignment quality depends on the precision and quality of such a surface.
To decrease the extreme requirements on the surface quality, both parts are supported in close proximity to their contact points or areas by the same part of the surface so that the alignment is expected to be reasonably good even if the aligning surface is n&lt;t absolutely precise on a larger scale.
The direct contact of the aligned ends with the aligning surface obstructs the access to the contact area between the aligned articles to various degrees. This complicates the application of coupling media or adhesives to the contact area. The devices which are the most efficient in aligning the fibers in a butt-to-butt fashion (such as the dry memory splicers described in the U.S. Pat. Nos. 07/288,628, 4,888,827) are the most difficult to use with coupling media and also leave the ends of the spliced fibers entirely inaccessible since the whole fiber circumference is in contact with the memory material.
Some connectors or splicers are equipped with thin channels allowing for the introduction of coupling media to the joint area. Such thin channels, however, are not sufficient to ensure the access to the joint to perform other operations since the major part of the joint area is still in direct contact with aligning surfaces.
Hence, current aligning mechanisms prevent any free access to the joint between the connected parts.
Barring the aforementioned X-Y-Z manipulators, there is no mechanism or device in the prior art which can align two parts with high precision by simple and inexpensive means and leave the joint between the parts accessible for inspection, cleaning, welding, gluing, fusing, or any other operation.